1. Technical Field
The presently disclosed technologies are directed to a system and method for improving paper path alignment by preventing contention between two belt transports in a direct marking hold-down transport system. The system and method described herein use a mounting bracket which allows for self-alignment of one transport relative to the other.
2. Brief Discussion of Related Art
In order to ensure good print quality in direct to paper (“DTP”) ink jet printing systems, the media substrate must be held extremely flat in the print zone. Conventional approaches use electrostatic tacking of media to a moving transport belt that is held flat against a platen in an imaging zone or printing zone. Conventional electrostatic tacking methods create a tacking field by primarily applying charges to a media substrate side that is not in contact with the tacking surface (transport belt). The charges can be applied by well-known methods in the art including the use of various non-contact corona charging devices or the use of various pressured devices, such as a biased roller. Generally, pressured devices such as bias rollers are preferred because the presence of mechanical pressure helps to tack stressful media such as curled or cockled media substrates. An undesirable side effect of electrostatic tacking of media substrates is the creation of a high electric field between the surface of the media substrate and the imaging heads (also referred to herein as print heads). As the media substrate travels in the printing zone, the high electrostatic field can affect the ink jetting, which results in print quality defects.
An additional drawback to the use of electrostatic tacking forces is that when multiple belt modules and tacking belts are used in a printing system, the electrostatic forces applied to each belt and/or module are quite large and if the multiple belt systems are not perfectly aligned this can result in large lateral forces at the intersection of the belts. This results in misalignment of the belts and can cause problems in printing or copying systems.
In order to solve this problem, a dual belt system designed to maximize hold-down while minimizing undesirable fields in the print zone is described in patent application Ser. No. 13/669,578, which applies electrostatic charges to the side of media that faces the belt transport while still maintaining high tack force. One concern with this approach is that large lateral belt forces can be seen if the two belt systems are not perfectly aligned.
Despite these efforts, misalignment may still be a problem. The media substrate, when tacked by electrostatic tacking methods, almost always produces an electric field. Accordingly, it is desirable to reduce the undesired effects of the electrostatic forces, and further preventing and/or correcting any misalignment of the media substrate processing path which may result as a result of the electrostatic forces.